For about the last fifty years, protective and decorative coatings based upon various polymeric resins have been increasingly used. These polymers have been utilized in many applications because they have provided a wide range of strength, flexibility, toughness, adhesion, degradation resistance and other film properties. Many polymers, however, are in dispersions or are solution polymers because they are prepared and used as a part of dispersions or solutions of polymers in organic solvents. In coatings technology, polymeric vehicles which include thermoplastic polymers require the use of organic solvents which often are toxic and/or subject to regulation that demand their reduction in coating compositions.
Environmental concern has become increasingly important. This concern not only extends to preservation of the environment for its own sake, but extends to safety for the public as to both living and working conditions. VOCs resulting from coating compositions which are applied and used by the industry and by the consuming public are often not only unpleasant, but contribute to photochemical smog. Governments have established regulations setting forth guidelines relating to VOCs which may be released to the atmosphere. The U.S. Environmental Protection Agency (EPA) has established regulations relating to the amount of VOCs released to the atmosphere, such regulations being scheduled for adoption by the states of the United States. Guidelines relating to VOCs, such as those of the EPA, and environmental concerns are particularly pertinent to the paint and industrial coating industry which uses organic solvents which are emitted into the atmosphere.
Polymerization reaction products of linseed oil and dicyclopentadiene as described in U.S. Pat. No. 2,443,044 to Lycan, et al. are known. These products however, are a result of linseed oil which has a low iodine value. Moreover, these prior art products are viscous or are gels and have a high dicyclopentadiene content. When these products are used as a part of polymeric vehicle for a coating binder, a high dicyclopentadiene content interferes with desired or required properties such as hardness, flexibility and impact resistance. Moreover, these prior art linseed oil copolymers resulted in viscous systems which were not suitable for keeping solvent content at a minimum to provide a low VOC formulated coating composition which could be readily applied with existing coating equipment.
In the prior art, there were no restrictions on the amount of solvents used in formulated coatings; hence, large amounts of solvents could have been and were used to bring viscosities of air dried polymeric vehicles and formulated coating compositions to acceptable levels for application to a substrate.
An object of the present invention is to provide a new linseed oil composition which is a copolymer of linseed oil and dicyclopentadiene and a method for making same.
Another object of the invention is to provide a polymeric vehicle which includes the copolymer of linseed oil and dicyclopentadiene and at least one other polymeric resin.
Yet another object of the invention is to provide a low VOC formulated coating composition which includes the polymeric vehicle of the invention.
Still further objects and advantages of the invention will be found by reference to the following description.